Ok I'm confused. My old Maverick door car, backhalf, SBF mounted to motor plates. 32x14, 9" Ford. 4 link. I have been chasing a vibration for a while and this past week I found a couple things. The engine/trans is angled downward (toward the rear) by 3°. Pinion angle I measured at 0.75° down (toward the front). driveshaft angle at the rear end is 0.75°.
What is the proper pinion angle? Measure the difference between the transmission tailshaft and the pinion, or the actual angle between the shaft and pinion? If I ask 3 different people (who are supposedly in the know) I get 4 different answers. Watched Tim McAmis youtube video and he references the difference between pinion and driveshaft but left out the tailshaft-to-driveshaft angle. Or does that make any difference in a drag application?
My method. Remove driveshaft and place it 100' or more from car to avoid confusion. Place car on boxes or drive on ramp,trailer or similar so suspension is loaded and easier if pinion yoke flats are vertical. Place the angle finder on the harmonic balancer and take a reading. Place the angle finder on the pinion yoke flats and take a reading. The difference is the pinion angle.
There ya go. The driveshaft being in the car always confuses the subject for many.
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Wow. That was unexciting. A thread about pinion angle that actually has the correct method!
We can address operating angle, but it may very well confuse a topic that has gone very well.
Foxtrot Juliet Bravo
At least 100 feet away!!!!!!!!
If your engine and trans is pointed-down in the rear by 3*, you will be pointing the pinion 1* upwards or so to get the angle to 2* down. I don't run a 4-link so I don't know if a -2* pinion angle is correct or not. Maybe you only want -1*, in that case you would rotate the pinion up 2*.
I have tried over the phone to explain pinion angle to someone and they always refuse to perform the first step. 100' is the bare minimum and it's better if you can place it in a separate building under lock and key so there is less temptation to reinstall before completing the job.
If your engine transmission is pointed down in the rear is it pointing up in the front?
Shaft is currently out.
3° down at rear of transmission. 3° up at the harmonic balancer. I will adjust the pinion as I think it should be, roughly 1-1.5°°+. I wish I could get the engine/trans more level, but on this car, it ain't happening without a lot of surgery.
The confusion results in people telling me to do it several different ways. I've always done it the way you guys described, short of throwing the driveshaft across the pond of course. I do it with the shaft in, usually try to shoot for about 2° to account for any rear end twist. I've also removed the shocks and moved the rear end through it's arc of travel and measured pinion angle throughout the travel. Did that right during the car's build many years ago.
It always leaves well just has had a small vibration the last time I had it out, that's why I'm going through the entire car.
If the engine/trans is pointing downwards 3*, putting the pinion angle at 0* will give you a net of -3*.
So if you want less than -3* (as you stated) you need to rotate the pinion up towards the floor.
Keep that driveshaft far, far away for all of this!
I put the angle finder on the balancer and the pinion on most cars.
On my race car I am lucky in that I can put the angle finder on top of my throttle body and op top of the fab 9" housing. I can actually leave the driveshaft in there and just pretend I don't see it!
I'm with everyone else. Take the driveshaft out and away as far as possible.
My engine/trans is pointed down at the back. I can't lower the front of the engine any more and the headers hit the floor preventing me from lifting the rear.
With 32" tall tires on a 4-link, the pinion sits higher in the car than the transmission yoke. The diff yoke is pointed upwards to match the same angle as the engine/trans. It looks strange and looks like the angles are excessive but I have no vibrations.
In a good chassis car, the crankshaft centerline should be aimed directly at the pinion yoke on the diff. Due to many production car setups and how much we modify them, this is normally hard to do unless you're building a tube chassis car.
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there are a lot of us that did it wrong for many years,lol.there are many places to get a reading on motor /trans ect.the difference between engine ect and pinion is the answer.
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On my junk, (digital angle finder) balancer is "alt 0", pinion flat is down 1*. It's a ladder bar car, more or less hasn't shown a difference to date so I leave it where it is.
The driveshaft WILL confuse you so take it out of the equation.
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